I do like doing a bit outside! But not this time of year! Private customers can be talked round but this bungalow we're doing for a builder won't wait. Done all inside now and scratched all outside. It's over grey thermalite blocks on most of it where the new walls are. And a few reds on the old but they're not big areas. We didn't put any waterproofer in to get the suction and we were goin to be topping it with a 6 1 1. But bit worried about the frost getting it in the early hours. Has anyone tried it with frost proofer in or rapid hardener? We've never bothered with it but thinking about giving it a go
Who else is still doin it outside?
- Thread starter Jim85
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Arti
Well-Known Member
Got a nice little wet-dash job on a gable-end to look forward to at the start of January, can't wait059.gif)
That bad boy there marra
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render does not key to those blocks, we always cover them in riblath. i would say no to work if they wanted render straight on to these blocks, to risky, and i do not want any problems.
Jace
Well-Known Member
got to start a rendering job tomorow helping out another spread i know he rang me and said he was desperate for another spread on the job he has 4 blokes on this wall already and he needs more:RpS_confused: must be a lump what ever it is, "thanks mate" wait till its cold then get me outside haha
Rigsby
TPF Special Forces
Thermalites are trouble for sand & cement. The strongest scratch coat needs to 6:1:1 or it could pull off. I now sbr thermalites and make it clear to the client of the risks.
You may have problems with to much suction with having no waterproofer. Your second coat may dry faster than you can rub it up. Wetting it down will help but flooding it will make it dry fast at the top and ripple at the bottom with the risk of so much water in the base and blocks if there is a frost around you could be in for trouble.
Do a trial m2 for suction and spray water accordingly, do not hose pipe it. As for frost proofers well if you had used a waterproofer you would need an accelerator (frost proofer) at this time of year to make it go off. Since you have not got waterproofer then it should suck in but the addition of a frostproofer will help it it gets a bit parky. Do not put on the second coat with frostproofer in too soon after the first. If the second coat cures faster than the first you could get crazing of separation.
I at this time of year put on a waterproof scratch then a second scratch without waterproofer and let it dry out. There is usually enough damp in the air to dampen the scratch with water and suction is about right.
You may have problems with to much suction with having no waterproofer. Your second coat may dry faster than you can rub it up. Wetting it down will help but flooding it will make it dry fast at the top and ripple at the bottom with the risk of so much water in the base and blocks if there is a frost around you could be in for trouble.
Do a trial m2 for suction and spray water accordingly, do not hose pipe it. As for frost proofers well if you had used a waterproofer you would need an accelerator (frost proofer) at this time of year to make it go off. Since you have not got waterproofer then it should suck in but the addition of a frostproofer will help it it gets a bit parky. Do not put on the second coat with frostproofer in too soon after the first. If the second coat cures faster than the first you could get crazing of separation.
I at this time of year put on a waterproof scratch then a second scratch without waterproofer and let it dry out. There is usually enough damp in the air to dampen the scratch with water and suction is about right.
Rigsby
TPF Special Forces
You pick up things as the years go by when you are a dedicated outdoor worker. For example, hack off and wash the wall down same day just to wash the dust off. The bricks will take some water in but by next day will have some suction but not 100% like summer. You need your waterproof scratch coat to suck in but not too much, leaving a bit of moisture in the cement to set and cure. The little bit of water there is to freeze will be looked after by the air entrainer in the built in plasticiser. Cover the scratch work up with debris netting and hope for some heat loss out of the building.
For render then as the post below but for dash then either frost proofer and cover up with debris netting as best as but not touching the pebbles or wait for the air frost to lift and have the gobbo mixed as soon as in the morning (it wont go off, too cold) and have on the wall by noon latest, covered and frost proofer in. Design it so the gobbo is set by night fall.
never had frost attack yet. I even had a 5:1 s&c plinth freeze solid on me at 2pm and apart from some surface crazing on the surface it is still there today. That was with some frostproofer in even though it froze. It was put on at -5c.
For render then as the post below but for dash then either frost proofer and cover up with debris netting as best as but not touching the pebbles or wait for the air frost to lift and have the gobbo mixed as soon as in the morning (it wont go off, too cold) and have on the wall by noon latest, covered and frost proofer in. Design it so the gobbo is set by night fall.
never had frost attack yet. I even had a 5:1 s&c plinth freeze solid on me at 2pm and apart from some surface crazing on the surface it is still there today. That was with some frostproofer in even though it froze. It was put on at -5c.
The builder has stainless meshed all the thermalites so hopefully it's alright. But we have done so many internal render and sets on these blocks and never had any come backs. Suction always seems fine. But as for this outside ill just do it how I was goin to I think just give it a light spray with the pump spray before I do it but its only 100mm above windows to soffit all the way round so there's no gables or big areas
Render Systems
Private Member
tell the builer to fcuk off end of.. he just wants or needs the job looking nice to get paid,,,,
Dansouthcoast84
Private Member
Rendaid the blocks for external. Internal float and set i pva them first
Arti
Well-Known Member
People seem to have trouble with these blocks some whats your secret Andy
plasterjfe
Private Member
did a two day scrape last week. thats it now
essexandy
The Lake Governor
You're working on something that's soft so think about your mix ratios.
Arti
Well-Known Member
Ive never rendered on these blocks before I was just curious so im assuming the scratch and top needs to be quite weak
essexandy
The Lake Governor
Exactly Arti keep it weak
scotsplasterer
Member
i bet your snips were buggerd by the end, the stainless is brutal.
i have rendered over thermolites many times, never had call back yet, mind you always on the inside though, no externaly
Rigsby
TPF Special Forces
I have in my earlier days gone over Thermalites with 5;1 and had no comebacks but in theory the risks are there.
It is interesting when you are looking at jobs when you outline the risks and in my case mention you have to use sbr or rend-aid. You have pointed something out that the competition hasn,t and often gets me the job. I have to mention it anyway to justify being more expensive and to cover myself if they say just do it as normal to save money.
It is interesting when you are looking at jobs when you outline the risks and in my case mention you have to use sbr or rend-aid. You have pointed something out that the competition hasn,t and often gets me the job. I have to mention it anyway to justify being more expensive and to cover myself if they say just do it as normal to save money.
essexandy
The Lake Governor
Yes mate I'll often up the lime to make the gear more workable as much as anything when making it weaker.
If you make sure that an 8:1:1 ratio cures properly it'll be plenty hard enough to paint and still look great thirty years down the line.
I always use fibres in both coats with S&C and even then still put stress patches in, and that's even on dense blocks. Now I'm starting to use the Parex gear I'll always fully mesh as I can't put fibres in.
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